No one becomes fully delusional overnight. It usually begins with a small, manageable delusion that then mushrooms into bigger ones, resulting in a chain-reaction escalation of self-deception. In the worst cases, it ends in institutionalization.

Thus has been the perilous journey of the emotionally fragile Republican ruling class.

First, they told themselves that Donald Trump, the flashy New York billionaire businessman who had flirted with running for the presidency in the past, would not run this time, either.

On June 18, he announced his candidacy.

The GOP elites then told themselves that given his notorious thin-skin, controversial history and previous unwillingness to disclose his finances, Mr. Trump would drop out of the race.

In midsummer, he made stopping illegal immigration, enforcing the border and constructing a barrier wall the centerpiece of his campaign, which catapulted him to front-runner status and kept him there.

The Republican powerbrokers then told themselves that given Mr. Trump’s outrageous statements and caustic personality, most GOP voters would come to their senses, get serious and fall in line as they have always done quite reliably. Mr. Trump, they argued, could not win a single primary state.

Then actual voting began. And the first-timer, the brash anti-politician, began racking up resounding victories in New Hampshire, South Carolina and Nevada. He even placed second in Iowa, an evangelical-heavy state that conventional wisdom suggested would never have even considered the New York showman in the first place.

The ruling elite’s current delusion is that Mr. Trump will not be the Republican nominee, even after he racked up seven wins this week, in places as diverse as Massachusetts and Georgia — and looks durably strong heading into the big contests later this month.

They remain deluded to the point of reportedly considering enlisting former failed GOP nominee Mitt Romney as a late entrant into the race — or recruiting Sen. Marco Rubio during a brokered convention — to try to derail Mr. Trump. If they were to try either of those Hail Mary passes, there would be a revolt among Republican voters that would make the current political earthquake look like a mere tremor.

It is not impossible for either Sen. Ted Cruz or Mr. Rubio to pull off enough of a rolling upset to deny Mr. Trump the required number of delegates to win the nomination outright. But Mr. Trump is in the driver’s seat, and whatever delusional plotting the elites may be cooking up is likely to detonate the party for once and for all. They accuse Mr. Trump of destroying the party, but they did that long ago.

After decades of fearing the power of the establishment, the electorate is finally fighting back. And they now have a candidate who mirrors the fearlessness and frustration they have long felt but could never channel effectively.

Like his style or not, Mr. Trump is an in-your-face guy. Voters want that kind of guy taking it to President Obama’s record, Hillary Clinton or whomever the Democrats nominate, and to the unbridled, destructive leftism that has rendered America virtually unrecognizable.

Past nominees Mr. Romney and Sen. John McCain were gentlemen, but gentlemen who take their feet off the gas don’t win presidential races. Ruthless mean guys do.

Mr. Trump isn’t constrained by the old gentlemen’s rules that for too long boxed in Republican presidential candidates. Mr. Cruz, who continues to give Mr. Trump a run for his money, is a die-hard conservative fighter, and even he has often fallen into the gentlemen’s trap — mostly because he is a gentleman.

Mr. Rubio has recently stepped out of the gentlemen’s trap to mock and attack Mr. Trump in the same street-fighter’s way Mr. Trump has engaged each of them. But Mr. Rubio may have waited too long to show voters that he can be as scrappy as Mr. Trump, who has already branded himself as the most effective street-fighter on the scene. You cannot beat the master at his own game.

Voters have had enough of Republican nervous Nellies. They don’t want another wimp who is going to play by the Democrats’ ground rules. If that happens, the Democrats will win again.

They may win anyway, but Republican voters do not want it to happen for lack of trying. This time, they want a GOP nominee who will be just as brutal and relentless as the Democrats are, who will return fire and who will, they hope, finally stand up for them.

Trump critics believe his supporters are kidding themselves to believe those things, but what is undeniable is that he has framed this race from the start and has been racking up victories. Nobody is delusional about that.